update_contactUpdate existing SendGrid contacts by submitting their contact ID and revised fields. Keep email marketing lists accurate with current names, addresses, phone numbers, and custom field values.
Update existing contact information
| Name | Required | Description | Default |
|---|---|---|---|
| contacts | Yes | Array of contact objects with updates |
Changes observed during successful MCP inspections.
v1.1.1Input schema / additionalPropertiesRemoved value: -falseInput schema / properties / contacts / items / additionalPropertiesRemoved value: -falseInput schema / properties / contacts / items / properties / custom_fields / propertyNamesAdded value: +{
+ "type": "string"
+}Input schema / properties / contacts / items / properties / email / patternAdded value: +"^(?!\\.)(?!.*\\.\\.)([A-Za-z0-9_'+\\-\\.]*)[A-Za-z0-9_+-]@([A-Za-z0-9][A-Za-z0-9\\-]*\\.)+[A-Za-z]{2,}$"v1.0.0Input schema / $schemaAdded value: +"http://json-schema.org/draft-07/schema#"Input schema / additionalPropertiesAdded value: +falseDoes the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already disclose that the operation is mutating, idempotent, and non-destructive, so the description carries less burden. The description adds only the 'existing' scoping constraint and does not explain partial-update semantics, custom_fields merging, or behavior for unknown contact IDs, leaving room for improvement.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, front-loaded sentence with no wasted words. The qualifier 'existing' appears early and the sentence is easy to parse, though 'information' is somewhat generic and could be replaced with more specific wording.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a relatively simple update tool, the schema and annotations cover the required id, optional fields, idempotency, and non-destructive nature. However, without an output schema, the description still omits important context such as whether omitted fields are preserved, how multiple contacts in the array behave, and what happens when an id does not exist.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, and the schema thoroughly documents the required id and all optional contact fields. The description adds no field-level meaning beyond the generic 'contact information', so it meets the baseline but does not enhance parameter understanding.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb ('Update') and resource ('contact'), and the qualifier 'existing' distinguishes it from create_contact and delete_contact among the siblings. It is slightly less precise than the schema's array-of-contacts capability, but the primary purpose is unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The word 'existing' implies this tool is for modifying contacts that already exist rather than creating new ones, giving some usage direction. It does not explicitly name alternatives or state when to prefer this over related contact read/list tools, so the guidance is implied rather than explicit.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.